I am shopping for a 40ish cruiser and was looking at some Valiants on Yachtworld. I noticed that they did not have rigid vangs. Is there a downside to having a rigid boom vang on a cruiser?

That bit of deck is often used for dinghystorage on the Valiant. Our Walker Bay fits just perfect there between the dodger and the mast, as ours didn't come with any sort of vang. Ours is a 1975, with end boom sheeting. We go back and forth with the dink between there and the foredeck, depending on circumstances.

Also, a lot of the Valiant owners tend to bring the vang forward and outboard as a preventer, which doesn't work with a rigid vang.

You either like them or don't. A soft vang can be used as a preventer (with the right precautions) and as mentioned storage aft of the mast is not doable with rigid. Nice if the boat has no boom gallows.

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